Hypoxic aircraft fire prevention system with advanced hypoxic generator

Abstract

An aircraft fire prevention system provides oxygen depleted (hypoxic) air for the fuel tank and/or cargo compartment protection; the system does not employ compressed air for the production of hypoxic air, which allows to save energy and fuel and to reduce negative impact on the earth atmosphere.

What is claimed is: 
     
       1. A system for providing fire prevention for a fuel tank on an aircraft by using cabin air for producing oxygen-depleted (hypoxic) air from the cabin air, said system comprising:
 an air-separation device having an inlet and first and second outlets; 
 said air-separation device employing a first pressure difference between said inlet and said first outlet, and a second pressure difference between said inlet and said second outlet; 
 said first pressure difference and said second pressure difference providing a driving force for separating said cabin air into oxygen-enriched and oxygen-depleted gas mixtures without preliminary compression; 
 said inlet communicating with an interior atmosphere of the aircraft, said first outlet communicating with one of a fuel tank or a cargo compartment, and said second outlet communicating with the atmosphere outside of the said aircraft; 
 said inlet receiving said cabin air and said first outlet transmitting an oxygen-reduced gas mixture and said second outlet transmitting an oxygen-enriched gas mixture; 
 said oxygen-enriched gas mixture being normally vented outside the aircraft; and 
 said oxygen-reduced gas mixture, when in use, being supplied into said fuel tank for maintaining therein a hypoxic environment in order to prevent fuel ignition or explosion; 
 wherein an oxygen content in said oxygen-reduced gas mixture is maintained in a range from 9% to 15%. 
 
     
     
       2. The system according to  claim 1 , wherein said oxygen-reduced gas mixture, when in use, is constantly supplied into said fuel tank or cargo compartment for maintaining therein a hypoxic environment in order to prevent fuel ignition or explosion. 
     
     
       3. The system according to  claim 1 , further comprising:
 said air separation device employing a hollow fiber air separation membrane. 
 
     
     
       4. The system according to  claim 1 , further comprising:
 said air separation device employing one of fuel cell technology, a PSA technology, or a VPSA technology. 
 
     
     
       5. The system according to  claim 1 , further comprising:
 said air separation device employing a combination of membrane and one of VPSA technology or PSA technology. 
 
     
     
       6. The system according to  claim 1 , further comprising:
 said inlet of the air separation device being provided with a compressed air when the aircraft is on the ground or at an altitude below 3 km above sea level, in order to provide continuous fire protection. 
 
     
     
       7. The system of  claim 1 , further comprising:
 said first outlet being provided with a vacuum pump. 
 
     
     
       8. The system of  claim 1 , further comprising:
 said first outlet communicating with a compartment onboard of the aircraft for providing fire protection. 
 
     
     
       9. The system of  claim 1 , further comprising:
 said inlet being provided with an additional fan for oxygen content regulation. 
 
     
     
       10. The system of  claim 1 , further comprising:
 an oxygen content monitoring system provided for measuring the oxygen content of the oxygen-reduced gas mixture transmitted via said first outlet; and 
 a computerized controller for receiving and analyzing data from said oxygen content monitoring system. 
 
     
     
       11. A method for providing fire prevention for a fuel tank on an aircraft by using cabin air for producing oxygen-depleted (hypoxic) air from said cabin air, said method comprising:
 employing a first pressure difference, by an air-separation device having an inlet and first and second outlets, between said inlet and said first outlet, 
 employing a second pressure difference by the air-separation device between said inlet and said second outlet; 
 receiving said cabin air by said inlet; 
 separating said cabin air, by using said first pressure difference and said second pressure difference as a driving force, without preliminary compression, into oxygen-enriched and oxygen-depleted gas mixtures; 
 said inlet communicating with an interior atmosphere of the aircraft, said first outlet communicating with one of a fuel tank or a cargo compartment, and said second outlet communicating with the atmosphere outside of the said aircraft; 
 transmitting by said first outlet an oxygen-reduced gas mixture; and 
 transmitting by said second outlet an oxygen-enriched gas mixture; 
 said oxygen-enriched gas mixture being normally vented outside the aircraft; 
 said oxygen-reduced gas mixture, when in use, being supplied into said fuel tank or cargo compartment for maintaining there a hypoxic environment in order to prevent fuel ignition or explosion; 
 wherein the oxygen content in said oxygen-reduced gas mixture is maintained in the range from 9% to 15%. 
 
     
     
       12. An apparatus for producing hypoxic air, said apparatus comprising:
 an air-separation device having an inlet and first and second outlets; 
 said air-separation device employing a first pressure difference between said inlet and said first outlet, and a second pressure difference between said inlet and said second outlet; 
 said first pressure difference and said second pressure difference providing a driving force for separating said cabin air into oxygen-enriched and oxygen-depleted gas mixtures without preliminary compression; 
 said inlet communicating with an interior atmosphere of the aircraft, said first outlet communicating with one of a fuel tank or a cargo compartment, and said second outlet communicating with the atmosphere outside of the said aircraft; 
 said inlet receiving said cabin air and said first outlet transmitting an oxygen-reduced gas mixture and said second outlet transmitting an oxygen-enriched gas mixture; 
 said oxygen-enriched gas mixture being normally vented outside the aircraft; and 
 said oxygen-reduced gas mixture, when in use, being constantly supplied into said fuel tank or cargo compartment for maintaining therein a hypoxic environment in order to prevent fuel ignition or explosion; 
 wherein an oxygen content in said oxygen-reduced gas mixture is maintained in a range from 9% to 15%. 
 
     
     
       13. A method of producing hypoxic air for fuel tank or cargo compartment fire prevention on an aircraft, said method comprising:
 extracting, by an air separation device according to  claim 12 , hypoxic air out of air contained in an interior compartment of an aircraft without preliminary pressurization of the air; 
 supplying said hypoxic air into said fuel tank or cargo compartment and creating there a fire preventative atmosphere; and 
 expelling an oxygen-enriched fraction of the air as a byproduct of the air separation into an atmosphere outside of said aircraft. 
 
     
     
       14. The method of  claim 13 , wherein a vacuum pump is provided at said first outlet for improved performance and oxygen content regulation. 
     
     
       15. The method of  claim 13 , wherein
 an additional fan is provided on said inlet for improving performance of the system and oxygen content regulation. 
 
     
     
       16. The method of  claim 13 , further comprising:
 wherein during a flight at altitudes above 3 km above sea level, said inlet receiving cabin air without preliminary pressurization and separating it into oxygen enriched fraction and oxygen reduced fraction; 
 said oxygen reduced fraction being provided into said fuel tank or cargo compartment, via said first outlet, for fire prevention and said oxygen enriched fraction being expelled into atmosphere outside of said aircraft, via said second outlet; 
 said inlet having upstream a valve that switches from a non-pressurized cabin air supply to a pressurized air supply; 
 a compressor that can supply said air separation device, via said valve, with compressed air when aircraft is on the ground or at an altitude below 3 km above sea level; 
 said valve closing compressed air supply when aircraft reaches an altitude high enough to provide air separation using pressure difference between cabin air and outside atmosphere and using suction provided by the fuel consumption in said fuel tank. 
 
     
     
       17. An apparatus for producing hypoxic air, said apparatus comprising:
 an oxygen-consuming device having an inlet and first and second outlets; 
 said oxygen-consuming device employing a first pressure difference between said inlet and said first outlet, and a second pressure difference between said inlet and said second outlet; 
 said first pressure difference and said second pressure difference providing a driving force for moving said cabin air through said oxygen-consuming device and converting said cabin air into oxygen-depleted gas mixture without preliminary compression; 
 said inlet communicating with an interior atmosphere of the aircraft, said first outlet communicating with one of a fuel tank or a cargo compartment, and said second outlet communicating with the atmosphere outside of the said aircraft; 
 said inlet receiving said cabin air and said first outlet transmitting an oxygen-reduced gas mixture and said second outlet transmitting byproducts of the oxygen consummation; 
 said byproducts being normally vented outside the aircraft; and 
 said oxygen-reduced gas mixture, when in use, being constantly supplied into said fuel tank or cargo compartment for maintaining therein a hypoxic environment in order to prevent fuel ignition or explosion; 
 wherein an oxygen content in said oxygen-reduced gas mixture is maintained in a range from 9% to 15%. 
 
     
     
       18. A method of producing hypoxic air for fuel tank fire prevention on an aircraft, said method comprising:
 extracting, by an oxygen-consuming device according to  claim 17 , oxygen out of air contained in an interior compartment of an aircraft without preliminary pressurization of the air and producing this way a hypoxic air; 
 supplying said hypoxic air into said fuel tank and creating there a fire preventative atmosphere; and 
 expelling a byproduct of the oxygen consummation into an atmosphere outside of said aircraft. 
 
     
     
       19. The method of  claim 18 , wherein a vacuum pump is provided at said first outlet for improved performance and oxygen content regulation. 
     
     
       20. The method of  claim 18 , wherein
 an additional fan is provided on said inlet for improving performance of the system and oxygen content regulation.